1. Field of the Invention
The present invention relates to an electric junction box mounted in a vehicle and the like, particularly to an electric junction box provided with a connection housing, such as a connector housing, open to a side of the electric junction box.
2. Description of Related Art
For efficient electric wirings and improvement in maintenance, electric junction boxes, such as junction boxes and relay boxes, have conventionally been used in electric systems of vehicles and the like. In general, such an electric junction box has a structure in which conductive members, such as a bus bar, that form an internal circuit are provided in an electric junction box main body having an hollow box shape composed of an upper case and a lower case combined with each other on an opening side. A plurality of connection housings are provided open to an upper surface and a lower surface of the electric junction box main body, the connection housings being provided therein with projecting connection terminals provided on bus bars. External electric components, such as connectors, fuses, and relays, are mounted and connected to the internal circuit.
With recent demands for downsizing and space saving, it is necessary to provide the connection housing open to a side surface of the electric junction box main body where the upper case and the lower case are combined, in addition to the upper surface and the lower surface of the electric junction box main body, so as to allow assembly of connectors of electric cable terminals and the like in a vehicle and to enhance the space efficiency of the electric junction box. In order to meet such demands, it is proposed that a housing half body is integrally provided to a peripheral wall of each of an upper case and a lower case and that the housing half bodies are combined as the peripheral walls are combined, and thereby a connection housing is provided open to a side surface of an electric junction box main body. Alternatively, Japanese Patent Laid-open Publication No. 2008-283760 discloses, for example, that a separately provided tubular connection housing is interposed between peripheral walls of an upper case and a lower case, and thereby a connection housing is provided open to a side surface of an electric junction box main body.
However, the connection housing having a divided structure that straddles the upper case and the lower case has a clearance in a locking portion of the cases. With an external force or vibration exerted, the cases may thus be displaced from each other, and the connection housing may deform. Such a deformation of the connection housing causes a displacement between the connection housing and a connection terminal projecting inside, thus possibly causing an electric component to hook as being mounted or causing difficulty in mounting. In addition, such a deformation of the connection housing causes instability of an electric component mounted inside the housing, thus leading to wear and damage of the electric component and the electric junction box as well as possibly causing a serious defect, such as a connection failure.
In the structure disclosed in Japanese Patent Laid-open Publication No. 2008-283760, it is necessary to interpose the separate connection housing between the peripheral walls of the upper case and the lower case, thus causing unfavorable conditions, such as an increase in the number of components, a complex structure, and a complicated assembly. Due to a certain clearance in the portion interposing the separate connection housing, in particular, the instability of the connection housing associated with the displacement of the cases cannot be completely solved. Thus, circumstances possibly remain to arise, such as a contact failure stemming from displacement with a contact portion.